Suction lifting devices have been used for a considerable period of time in association with mobile lifting and conveying devices. See, for example, the disclosure of U.S. Pat. No. 2,899,089. Such devices have been primarily used to lift and transport heavy loads, usually large single items such as sheets of glass, pipe, packages and the like.
More recently, it has become a common practice to pave parking lots, walks, parks and even building roofs with particularly designed concrete slabs or bricks since these provide great durability and functionality as well as unique and attractive appearances. Generally such slabs or bricks must be normally and individually laid so that proper spacing between them is maintained. One way to machine lay individual bricks or slabs is shown in my co-pending U.S. patent application Ser. No. 07/234,117 entitled VACUUM LIFTING DEVICE; however, there are few devices available that are suitable for lifting and laying a plurality of slabs or bricks in layered form at one time. Each slab or brick can weigh up to 10 pounds or more and therefore in the aggregate represent a sizeable load if a layer is to be lifted and placed in one operation.
Bricks or slabs often utilized in the activity described are usually manufactured in batches of about 40 bricks using a grid resembling a plurality of egg crates or cookie cutters placed in a side-by-side relationship. The grid is made of thin steel and is constructed to extend slightly above the finished brick. The grid, which is open on both sides, is placed on a flat surface and filled with concrete. A hydraulic ram with as many brick shapes as there are openings in the grid is brought down in registry with the grid, and the concrete is compacted to eliminate voids. The grid is then lifted relative to the ram and the formed bricks are pressed out on a curing sheet to dry and cure. After the concrete is set, the group of bricks is deposited, one layer upon another, until about 10 layers are built up on a pallet for shipment to the job site.
There have been several attempts to provide a lifting and transporting mechanism to handle layers of bricks or slabs. One device is provided with a clamp that extends down along the sides of a layer of bricks and exerts horizontal pressure against the brick sides to bind the bricks together and permit the layer which can weigh approximately 400 pounds to be moved and placed without dropping the load. A number of disadvantages are associated with this technique. First the clamp jaws have to extend at least to the mid point of the brick height. If the brick layer is aligned on two sides to brick already laid, the layers are separated from the other laid layers by the thickness of the edge of the clamp. Secondly, when the device carrying the clamp is lowered to allow the clamped bricks to align with previously laid bricks, there is only about 1 inch of brick exposed below the clamped jaws. From a practical standpoint this is not enough height since the equipment does not allow for minute adjustment, and the operator's vision is impaired by the clamping means extending beyond the brick edges. Additionally, the clamping force necessary to support the bricks is great and the bricks are pressed together as much as possible. When they are brought into alignment with laid bricks that have been allowed to relax and separate, they will not fit tightly into the openings of the relaxed bricks already laid. A discernible and undesirable open joint is left.
Another system utilized a vacuum to lift a layer of bricks in unison. In that system, a rectangular plenum supports a plurality of tubular sleeves each of which extends downwardly to engage a brick of the layer to be lifted. Each rigid vacuum connection has a short, contractable corrugated tube connected to it. The other end of the tube is connected to the puck that contacts a brick. These collapsible tubes are as large in diameter as the brick shape will allow so that when suction on the brick is established, the corrugated tube will maintain its diameter but will shorten. While this system seems to work effectively, it is very expensive to construct and does not provide a finite adjustment feature that allows a laid layer of brick to relax naturally and blend in with adjacent previously laid layers.
The primary objective of the present invention is to provide a device that will lift a layer of bricks formed as described from a pallet and deposit the layer in a preselected location and configuration on the prepared site.
Another objective of the present invention is to provide a suction lifting device of the type described that is relatively inexpensive to build, easy to operate, and capable of some discrete adjustments to allow the individual bricks within a lifted layer to move slightly with respect to each other to thus become relaxed and to thereby blend in with adjacent laid layers without leaving a noticeable open joint therebetween.
The present invention comprises a supporting means, a load bearing member and a frame having a vacuum plenum associated with it. The frame is supported by the load bearing member and can be operably positioned in predetermined locations by an operator. A plurality of vacuum pucks are supported by the frame and vacuum plenum through a plurality of flexible tubular members connecting each of the pucks to the plenum. A puck alignment plate engages the tubular members and moves from the pucks toward the frame and back again as a layer of bricks are engaged, lifted and transported to the location where it is to be laid. A vacuum source is connected to the device through an appropriate vacuum line. Most often, the device is mounted on a self-propelled lifting and conveying apparatus such as a forklift truck.